This gets into what do you call a controller. Used to be they used separate chips mostly because they could not build anything better. Now to save money they put it all on the same silicon. There are still parts on the chip dedicated to each port like the memory buffers etc. They do share the connection to the pci bus but the older devices had a single separate chip that did that function also. I am not knowledgeable enough to know what advantage either design has. I know they are separate enough you can assign them directly to different VM in the current models.
I know we had boxes of those old cards we took out of servers when they were being scrapped. I doubt they were ever used because most servers went to thinner...